Online Encyclopedia

Search over 40,000 articles from the original, classic Encyclopedia Britannica, 11th Edition.

CERUSSITE

Online Encyclopedia
Originally appearing in Volume V05, Page 762 of the 1911 Encyclopedia Britannica.
» Make a correction to this article.
» Add information or comments to this article.
Spread the word: del.icio.us del.icio.us it!

CERUSSITE , a See also:

mineral consisting of See also:lead carbonate (PbCO3), and an important ore of lead. The name (sometimes erroneously spelt cerusite) is from the See also:Lat. cerussa, " See also:white lead." " Cerussa nativa " was mentioned by K. See also:Gesner in 1565, and in 1832 F. S. See also:Beudant applied the name ceruue to the mineral, whilst the See also:present See also:form, cerussite, is due to W. See also:Haidinger (1845). Popular names in See also:early use were lead-spar and white-lead-ore. Cerussite crystallizes in the orthorhombic See also:system and is isomorphous with See also:aragonite. Like aragonite it is very frequently twinned, the See also:compound crystals being pseudo-hexagonal in form. Three crystals are usually twinned together on two faces of the See also:prism m { 11o1, producing six-rayed stellate See also:groups (See also:figs. , and 2) with the individual crystals intercrossing at angles of nearly 6o°. Twinning on the faces of the prism r { 1301, ; the angles of which are also nearly 6o°, produces a similar See also:kind of grouping, but is much less See also:common.

Crystals are of frequent occurrence, and they usually have very See also:

bright and smooth faces. The mineral also occurs in compact granular masses, and sometimes in fibrous forms. It is usually colourless or white, sometimes See also:grey or greenish in tint; it varies from transparent to translucent, and has an adamantine lustre. It is very brittle, and has a conchoidal fracture. Hardness 3-32; sp. gr. 6.5. A variety containing 7% of See also:zinc carbonate, replacing lead carbonate, is known as iglesiasite, from See also:Iglesias in See also:Sardinia, where it is found. The mineral may be readily recognized by its characteristic twinning, in See also:conjunction with the adamantine lustre and high specific gravity. It dissolves with effervescence in dilute nitric See also:acid. Before the See also:blow- See also:pipe it fuses very readily, and gives reactions for lead. Cerussite occurs in metalliferous See also:veins in association with See also:galena, and has been formed by the See also:action of carbonated See also:waters on the galena: it is therefore found in the upper parts of the lodes FIG. 2.

together with other secondary minerals, such as See also:

limonite. Finely crystallized specimens have been obtained from the Friedrichssegen mine near See also:Ems in See also:Nassau, Johanngeorgenstadt in See also:Saxony, Mies in Bohemia, Phenixville in See also:Pennsylvania, Broken See also:Hill in New See also:South See also:Wales; and several other localities. Delicate acicular crystals of considerable length were found See also:long ago in the Pentire Glaze mine near St Minver in See also:Cornwall. It is often found in considerable quantities, and contains as much as 771% of lead. (L. J.

End of Article: CERUSSITE

Additional information and Comments

There are no comments yet for this article.
» Add information or comments to this article.
Please link directly to this article:
Highlight the code below, right click, and select "copy." Then paste it into your website, email, or other HTML.
Site content, images, and layout Copyright © 2006 - Net Industries, worldwide.
Do not copy, download, transfer, or otherwise replicate the site content in whole or in part.

Links to articles and home page are always encouraged.

[back]
CERTALDO 		[next]
CERUTTI, GIUSEPPE ANTONIO GIACHIMO (1738-1792)

Site © 2006 - Net Industries